PROJECT SUMMARY/ABSTRACT Alcohol use disorder (AUD) and posttraumatic stress disorder (PTSD) are complex psychiatric conditions that commonly co-occur. The AUD/PTSD comorbidity is marked by a more costly, severe, and chronic clinical course, when compared to either disorder alone. Current treatment approaches for AUD/PTSD are characterized by small effect sizes and significant attrition. A key avenue for informing our understanding of AUD/PTSD includes focusing our scientific attention to transdiagnostic, malleable mechanisms that significantly impact the AUD/PTSD comorbidity. Global sleep disturbance represents one potential contributor. Specifically, global sleep disturbance, particularly among those with PTSD symptoms, may contribute to the maintenance of the AUD by increasing reactivity to negative emotionality, which may thus increase alcohol craving. Against this background, the objectives of the current application are to: (a) determine the extent to which PTSD symptom severity is associated with alcohol craving as measured by emotional reactivity to alcohol and trauma cues and (b) examine global sleep disturbance as a moderator of the relationship between PTSD symptom severity and alcohol craving as measured by emotional reactivity to alcohol and trauma cues. The central hypothesis of this project is that global sleep disturbance moderates, or exacerbates, the relationship between PTSD symptom severity and alcohol craving as measured by emotional reactivity to alcohol and trauma cues. The approach is to recruit 60 individuals for a cue-reactivity experimental paradigm that will test the effects of PTSD symptom severity and global sleep disturbance on alcohol craving as measured by emotional reactivity to alcohol and trauma cues. Study candidates will meet criteria for current (past month) DSM-5 AUD, reporting a history of trauma exposure per DSM-5 PTSD Criterion A, and current (past month) subclinical (one symptom per cluster) or diagnostic DSM-5 PTSD (N = 60). At the completion of this project, it is the expectation that the effects of PTSD symptom severity and global sleep disturbance on alcohol cue reactivity will be further elucidated. The impact of this study is improved understanding of mechanisms related to AUD/PTSD, a complex comorbidity with significant health burden. The proposed project coordinates with the mission statement of the National Institute of Alcohol Abuse and Alcoholism (NIAAA) with its emphasis on the health risks of alcohol consumption, prevention, and treatment, and with its emphasis on increasing the understanding of normal and abnormal behavior relating to alcohol use. Ultimately, in accord with the strategic planning goals of NIAAA, the research findings will be translated and disseminated to health care providers, researchers, policymakers, and the public. In sum, this award will support substantial training in research methods, statistical analysis, and dissemination to a promising young researcher and will address a significant need for an experimental investigation of the effects of PTSD symptom severity and global sleep disturbance on alcohol cue reactivity among those suffering from AUD/PTSD.